Climate change is a more important driver of migration than income and political freedom at origin countries combined, and that figure may even be underestimated, says a leading researcher on the interplay between climate and migration.

New findings are just the tip of the iceberg reports Lisa Cornish for Devex. Combining migration flows between 198 origin countries and 16 Organisation for Economic Co-operation and Development destination countries across 35 years with significant weather and temperature data, the findings of a collaborative study between Dennis Wesselbaum, economics researcher at the Otago Business School, and Amelia Aburn, from Victoria University of Wellington, provided evidence for climate migration’s impact — and the reality of climate refugees.

Wesselbaum explains that the true impact of climate on the world’s movement is underplayed by poor data. He called for more investment in quality research and said governments need to better prepare for the political implications of a doubling or more of global migration.

A variety of sources contributed to the dataset as the basis for looking at migration flows between origin and destination countries — including data from the United Nations and OECD. But to understand causes, influences outside of the data need to be determined — including political instability, income at the destination country acting as a pull for migrants, and environmental factors.

“We bunched together the data and crunch numbers to look at various driving forces,” Wesselbaum explained. “The wage gap, distance between countries which is a proxy for how costly it is to migrate from one country to another, policy variables, and then on top we add climate change variables, such as temperature and weather-related disasters.”

This approach enabled Wesselbaum and Aburn to see the growing impact of climate, currently the third largest overall reason for migration. “To put it into perspective, the wage gap is still the most important factor followed by cost and then climate,” Wesselbaum said.

While these outside forces — wages opportunities and cost to migrate to destination countries — are leading factors of migration, climate is the strongest force within origin countries. The conclusion, and the other evidence available, suggests that climate change will increasingly have strong effect on less-developed country, particularly in countries that don’t have good social security, and limited mobility within their country.